FRAGMENTS OF SCIENCE. 



H3 



blowing at times over ten metres per second. 

 " These experiments," he says, " have given 

 the most interesting results that I have ar- 

 rived at since I began." With a wind ve- 

 locity of six or seven metres per second, the 

 sailing surface of eighteen square metres 

 carried him against the wind in a nearly 

 horizontal direction from the top of the hill 

 without even having to run at the start, as 

 is generally necessary. In a stronger wind 

 he allows himself to be simply lifted by the 

 wind from the hilltop and sail slowly against 

 it. As experiments have shown, the sailing 

 path is directed strongly upward by increas- 

 ing wind force, and this fact causes him 

 sometimes to be higher in the air than he 

 was at his original starting point. In this 



position his apparatus has occasionally come 

 to a standstill ; and this leads him to make 

 the following interesting statement : " At 

 these times I feel very certain that if I leaned 

 a little to one side, and so described a circle, 

 and further partook of the motion of the 

 lifting air around me, I should sustain my 

 position. The wind itself tends to direct this 

 motion. I have made up my mind by means 

 of either a stronger wind or by flapping the 

 wings to get higher up and farther away 

 from the hill, so that, sailing round in cir- 

 cles, I can follow the strong uplifting cur- 

 rents and have sufficient air space under and 

 about me to complete with safety a circle, 

 and lastly to come up against the wind again 

 to land." 



MINOR PARAGRAPHS. 



In a recent report to the French Academy 

 of Medicine, M. Henri Monod says that from 

 January, 1895, since the knowledge of anti- 

 diphtheritic serum and its uses has been 

 extensively diffused throughout France, the 

 statistics have shown a marked diminution in 

 the mortality from the disease. In the popu- 

 lation of one hundred and eight cities in 

 France, each having more than twenty thou- 

 sand inhabitants (the only places from which 

 the reports are sent to the central administra- 

 tion), during the first six months of the seven 

 years preceding 1895 — that is, from 1888 to 

 1894 — the average number of deaths was 

 twenty-six hundred and twenty-seven. Dur- 

 ing the first six months of 1895 the diminu- 

 tion was 65'6 per cent. This diminution is 

 not simply continuous, but is steadily increas- 

 ing, as is proved by statistics from month to 

 month. In a little pamphlet on this subject by 

 Dr. Welch, of the Smithsonian Institution, he 

 says that " the study so far of the results of 

 the treatment of over seven thousand cases 

 of diphtheria by antitoxine demonstrates be- 

 yond all reasonable doubt that an tidiphth cri- 

 tic serum is a specific curative agent for 

 diphtheria, surpassing in its efficacy all other 

 known methods of treatment for this dis- 

 ease," while " the essential harmlessness of 

 the serum has been demonstrated by over a 

 hundred thousand injections." 



An accident of considerable scientiSc in- 

 terest recently resulted m the photographing 



of a meteor. On November 23d last, at about 

 ten minutes past twelve at night, Mr. C. P. 

 Butler, of Knightsbridge, with the intention 

 of focusing and testing the field of a new 

 lens, placed a quarter-plate camera on the 

 window sill, pointed it roughly at the region 

 near the boundaries of Perseus, Andromeda, 

 and Aries, and exposed it for about ten min- 

 utes. Upon developing the plate, the track 

 of a meteor was the first impression to be 

 perceived. Confirmation of the occurrence 

 of the meteor is given by its having been ob- 

 served from the South Kensington Observa- 

 tory, both the time of the fall and the esti- 

 mated region of its path being identical with 

 the above observations. 



M. Berthelot, says Industries and Iron, 

 with the view of avoiding the inaccuracy 

 arising from the unknown or irregular ex- 

 pansion of the containing vessel of the gas 

 thermometer, has recently been experiment- 

 ing with a new method of measuring tem- 

 peratures. He employs the varying refrac- 

 tive power of gases at different densities. A 

 given refraction always corresponds to a 

 given density, though the pressure and tem- 

 perature may be different. The principle is 

 applied by the method of interference. A 

 luminous beam is split up into two parts, 

 which traverse two tubes filled with the same 

 gas, and the initial appearance of the inter- 

 ference fringes is noted. One of the tubes 

 is then raised to the temperature which it is 



